This invention relates generally to contour rough abrading, texturing fine abrading, and extra fine polishing of spherical surfaces utilizing the hardness and sharp irregular edge characteristics of crystalline diamond particles. Diamond particles of a specific uniform size are dispersed throughout a non-metallic thermosetting resin material that is molded and cured into a thin wall, cylindrical configuration and mounted to a rigid material tool body. More particularly this invention is adaptable to spherical contouring, surface texturing, finishing and polishing a bowling ball by being used as a non-rotating device on a rotating spherical surface or as a rotating device on either a rotating or non-rotating spherical surface.
Bowling ball performance is dramatically affected by the surface condition of the bowling lane. The light, medium or heavy oil content applied by a Bowling Center""s maintenance crew to the surface of the bowling lane affects the spin physics and performance of a bowling ball. To counteract the bowling lane conditions, serious bowlers use specific surface textures and finishes on the surface of their bowling balls. They also require the ball to have a close tolerance spherical radius for optimized bowling ball performance.
Extensive usage causes a bowling ball to become grooved on the surface from the repeated sliding along the lane. When this takes place, the ball becomes out-of-round and needs to be resurfaced with a new spherical radius. Another out-of-round situation occurs when plugging existing finger holes. This operation leaves excess material on the surface of the ball that must be blended with the object""s surface and made to conform to the object""s spherical radius.
The concept of resurfacing and refinishing the surface of bowling balls is not new. The previously mentioned problems are old ones and have been addressed often. For surface maintenance, tools made according to this invention""s specification would contain fine or extra fine abrasive particles of a size sufficient to remove scratches and polish the bowling ball. For major resurfacing, tools would contain coarse abrasive particles of a size suitable to remove larger surface imperfections. To restore a bowling ball manufactured with a textured surface, tools would contain medium size abrasive particles of a select size.
The abrading cup applications discussed in the following patent literature can be replaced with a cup or cups designed and manufactured according to this invention, simplifying and improving the efficiency of bowling ball surface manufacture, repair or surface maintenance while maintaining bowling ball sphericity.
U.S. Pat. No. 3,024,578 shows a complete machine having two, integral rotating abrading cups fitted with a conical, replaceable abrasive element in each cup, contacting the spherical surface as a circular line. The replaceable abrasive element supported by each cup initiates the abrading action on the surface of the ball until the abrasive media is worn from the element and requires replacement.
U.S. Pat. No. 3,133,383 shows a complete machine having three integral rotating abrading cups contacting a bowling ball in a circular surface pattern, i.e., a line or zonal surface contact used to grind, lap, and polish the surface of a spherical or truncated spherical ball. An external grinding or lapping compound is applied to the ball, causing the internal surfaces of the cups to grind and lap the ball in the region of contact.
U.S. Pat. No. 3,961,448 shows a complete machine having three integral rotating abrading cups contacting the spherical surface as an annular contact surface along the circular brim of the polishing cup. Before the polishing cups are able to initiate the abrading action on the body surface, an abrasive compound or abrasive slurry must be applied externally to the object.
U.S. Pat. No. 3,971,164 shows a bowling ball resurfacing machine where a series of rollers on a sliding table support the bowling ball while it is brought against a rotating flat disk fitted with an abrasive sanding media making a point contact on the surface of the ball. The ball is moved laterally to the sanding disk and then manually rotated to abrade the ball surface. The flat rotating sanding disk abrades the object""s surface as a point contact.
U.S. Pat. No. 4,856,231 shows a machine for grinding large balls in which a motor rotates the ball against a dish-shaped grinding tool located on top of the ball. An abrasive agent is supplied externally through the central opening of the grinding tool.
U.S. Pat. No. 5,484,329 shows a non-rotating, multicavity handheld tool with a hook and loop system to attach abrasive pads for sanding and polishing the surface of a rotating bowling ball. This pliable system, using replaceable abrasive pads, polishes the surface of the object while following the contour of the ball. Since it is a pliable system, the tool follows the rises and depressions on the ball surface and does not make the ball spherical if it is out of round.
U.S. Pat. No. 5,613,896 shows a bowling ball resurfacing machine with three integral rotating, grinding and lapping cups, each having an interior conical surface. Industrial diamond particles are nickel electroplated to the conical, annular ring that contacts the spherical surface as a circular single line.
U.S. Pat. No. 1,604,517 shows an annular body groove and a ring assembly for locating and clamping the abrasive grinding member to the tool body. xe2x80x9cThe tapered cross section of the grinding member makes it suitable for operation on generated involute gear teethxe2x80x9d which in turn subjects the grinding member to external bending forces. A larger annular mounting surface on the abrasive member is required to counteract the induced member forces encountered during grinding on the converging abrading surfaces. The added surface becomes suitable for clamping and replacing the member on the tool body.
U.S. Pat. No. 3,016,662 shows a honing element with a concave abrading face. The abrasive-filled honing member is friable in nature, made from a vitrified material that easily abrades and conforms to the configuration of the object during the honing operation. Concentric inner and outer annular supporting cylinders are required to reinforce and support the frangible abrasive element during the honing operation.
U.S. Pat. No. 5,658,188 shows a tool assembly with a circular grinding face extending outward and spreading toward the outside tool diameter having a uniform layer of abrasive grains bonded to the planar facial surface. During operation the abrasive surface on the tool is tangent to the spherical surface of the object being ground, and the radius of curvature of the tool is greater than the object""s radius. The slits disposed on circumferential spacing about the grinding faces help to expel the shavings but can be omitted as stated in the patent description.
U.S. Pat No. 2,982,057 shows two concepts of abrading tools used to achieve a honing effect by removing a minimum amount of material from a hard surface of a pre-ground frusto-spherical steel object. The first concept shows a hollow cylindrical member formed from an abrasive material; the tool is formed into a concave surface at its abrading end. During the honing operation, the abrading surface engages the spherically shaped object and polishes it. The second concept is a hollow cylindrical member of a hard cutting material formed at one end with spaced teeth having inwardly inclined working surfaces. The conic working surfaces of the teeth are tangent to the surface of the pre-machined spherical shaped object. In cross sectional view the point of contact between tool face and object moves upward along the surface of the inclined tool face as the tool is fed into the object. Honing stops as the object attains the required surface finish.
U.S. Pat. No. 4,001,981 shows a cup-shaped grinding wheel consisting of an annular conic-shaped, abrasive-filled ring of uniform thickness secured to the outside of an interior non-abrasive porous resin member. This assembly is secured to an annular support member. The finished grinding wheel is a typical configuration suitable for flat surface material removal.
This invention provides a tool assembly for abrading the spherical surface of a bowling ball designed to satisfy the aforementioned needs while maintaining the object""s spherical radius. The tool assembly is composed of two cylindrical components: a tool body and an abrasive-filled resin cylinder. The tool body is smaller in diameter than the spherical object being abraded and is fabricated from a hard rigid material. The diamond particle-filled, thin wall cylinder is smaller in diameter than the tool body and made from a molded and cured thermosetting resin material. The two components of the invention are assembled with their axis of rotation concentric with each other, and the abrasive-filled cylinder is located and fastened in the tool body groove whose cylinder height is greater than the depth of the body groove, resulting in one end of the cylinder extending beyond the tool body face. The extended cylinder face is machined to match the spherical radius of the object being abraded and cut in a radial direction across the cylindrical wall thickness to divide the face into circular arc segments. Cutting the circular face of the abrasive cylinder into two or more segments becomes necessary to wet the diamond abrasive cutting surface and to provide flow paths for excess coolant, lubricant and surface residue to drain from the tool body cavity area during operation. The coolant and lubricant application itself is a processing requirement when abrading and polishing spherical surfaces and is not part of this invention.
The physical average particle size of the diamond or other abrasive media dispersed throughout the molded and cured tool cylinder is sized for the particular abrading action being accomplished. The coarser particles are classified as mesh sizes (specification ANSI 1374 16) and the finer particles are classified as powder in micron sizes (specification ANSI B74.20). Size ranges, for example, include but are not limited to: coarse particles 30 to 230 U.S.A. mesh size for contour abrading, medium size particles 230 to 700 U.S.A. mesh size for surface texturing, fine powders 25 to 6 microns for fine surface finishing, and extra fine powders 6 to 1 micron for polishing the spherical surface of a bowling ball.
The tool body face opposite the abrasive-filled cylinder has machined holes to adapt the invention for various methods of usage including but not limited to the following: a handle fastened to the tool body face for manual handheld abrading actions, an adapter shaft fastened to the tool face for attaching a drill motor for rotational abrading, or a flange fastened to the tool body for adaptation to a powered drive shaft used on bowling ball surfacing machines. More importantly the invention is a tool assembly that will abrade and restore the surface of a bowling ball to the required manufacturer""s specification or customer""s requirements without loss of its sphericity when used in one of the methods described.